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P0641 Fault in 2003 Chevrolet Silverado 2500 6.0L Diesel - No Oil Pressure After HID Light Kit Installation

Model: Chevy 2500 Fault Code: P0641 Posted: 2017-01-02 05:25

I recently installed a plug-in-and-play HID light kit in my 2003 Chevrolet Silverado 2500 6.0L gasoline truck, and now the vehicle is experiencing severe issues. The truck will not maintain oil pressure, stalls after just seconds of running, and has developed multiple diagnostic trouble codes (DTCs), with P0641 being the primary one. The problem began after I disconnected a driver-side HID bulb during installation. At that moment, I observed a visible electrical surge—about an inch long—traveling from the bulb to the wire while the bulb was still unplugged. The positive side of the circuit was affected, and after reconnecting, the HIDs failed to function initially. I switched bulbs and then replaced the entire HID kit, which restored light operation—but triggered the check engine light. After removing the HID kit entirely and disconnecting the battery for several hours (with no change), the issue persisted. The oil pressure gauge behaves erratically: it rises to full capacity and then drops abruptly to zero before the engine stalls. This behavior only occurs after driving, and the problem did not exist prior to installing the HIDs. I have used an OBD2 code reader to monitor the system. While P0641 was initially the only code, subsequent drives resulted in additional sensor-related codes. The truck runs fine for short periods but then shuts down unexpectedly. I’ve also noticed that after turning off the engine and restarting, it often fails to start or stalls immediately. I suspect a wiring or electrical interference issue related to the HID installation, especially since the 5V reference circuit shared by key sensors (MAP, EGR, and Engine Oil Pressure) may have been compromised. I am now considering disconnecting the oil pressure sensor or replacing the ECM, but I want confirmation before proceeding. Can anyone confirm whether P0641 is typically linked to electrical interference from aftermarket lighting systems in 2003 Chevy 2500 6.0L trucks? What steps should I take to diagnose the 5V reference and ground circuits for these sensors?

Related fault codes
P0641
Comments (8)
Anonymous 2017-01-02 09:27

P0641 is the only code present—has it been confirmed that no other aftermarket devices or wiring were added? Ensure all modifications are properly isolated. Do you have an OBD2 scanner with freeze frame data capability?

Anonymous 2017-01-02 16:07

I removed both HID kits completely and have not added any other components. The issue only appeared after installation. I’ve disconnected the battery for several hours, but the problem remains. My OBD2 reader shows P0641 as the primary code. After driving briefly, the truck stalls and oil pressure drops to zero. I’m considering replacing the ECM or bypassing the oil pressure sensor via jumper wire—any advice on testing this safely?

Anonymous 2017-01-02 16:10

I experienced a similar issue: initially only P0641, then after driving for some time, the low oil pressure warning appeared. I turned off the engine due to rough shifting and poor idle. After stopping, multiple codes began appearing—this suggests a sensor or circuit failure triggered by electrical stress.

Anonymous 2017-01-02 17:06

P0641 should be investigated by checking the 5V reference circuit for the following sensors: Manifold Absolute Pressure (MAP), Exhaust Gas Recirculation (EGR) valve, and Engine Oil Pressure (EOP) sensor. These three share a common 5V bus—failure in one can degrade readings across all. Begin with EGR wiring integrity. Check voltage on the reference circuit and return path. Also verify ground connections for shorts to power.

Anonymous 2017-01-02 19:02

The issue started during my drive home after installation. The oil pressure gauge read around 550 psi throughout the trip, but when I reached my driveway, it dropped sharply and then stalled. No codes lit up at that moment—only after further driving did P0641 appear.

Anonymous 2017-01-02 19:03

After a few minutes of driving, the oil pressure reading dropped to zero and the engine immediately stalled. This behavior has repeated multiple times since then.

Anonymous 2017-01-02 19:04

How can I access freeze frame data from my OBD2 scanner to determine the exact sensor values at the time of fault occurrence?

Anonymous 2017-01-03 15:25

Use your OBD2 scanner to retrieve freeze frame data. For P0641, start by verifying the 5V reference voltage on the MAP, EGR, and EOP sensors. Check both reference and return circuits for proper signal levels. Also inspect ground connections—look for any shorted grounds or unintended power paths that could interfere with sensor readings.